Download 3D Thin Film Transistor Simulation

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APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
3D Thin Film Transistor
Simulation
© Crosslight Software, Inc., Vancouver, BC, Canada, (604)320-1704, www.crosslight.com
Contents
1. Introduction
2. Process simulation
3. Physical models and parameters
4. Results
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
1. Introduction
Amorphous silicon thin film transistors (a-Si:H TFTs) have been
widely used in the active-matrix flat panel display due to the low
process temperature, uniform device characteristics over large area
and low fabrication cost .
3D simuation of TFT is carried out by Maskeditor, CSUPREM and
APSYS.
 MaskEditor is used to generate mask layers. Commands for use
by subsequent tools may be added to each layer to generate the
device structure.
 CSUPREM is used to generate the device structure based on the
commands defined by MaskEditor. Process simulation may also be
performed without using MaskEditor.
 APSYS is used to simulate the electrical and optical properties of
the TFT device. Stand-alone device simulation may also be performed.
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
2. Process simulation
TFT mask patterns defined in MaskEditor:
•Red mask is used to etch the gate.
•Brown mask defines the active part.
•Blue mask used to generate the contact.
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
2. Process simulation
Process Flow
next page
In order to view structure clearly, the SiO 2
thickness is limited to 0.1 μm. Aluminum is then
deposited with a thickness of 0.18 μm and the
red mask is then used to generate the gate.
The next step is to deposit 0.35μm of SiN and 0.13μm
of intrinsic a-si. The brown mask is then used to
generate the active area.
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
2. Process simulation
Deposition of 0.15μm a-si with a resistivity
of 30Ω*cm.
Generation of the contact with the blue mask.
©©2010
2010Crosslight
CrosslightSoftware,
Software,Inc.,
Inc.,Burnaby,
Burnaby,BC,
BC,Canada
Canada www.crosslight.com
www.crosslight.com
APSYS
APSYS| CSUPREM
| CSUPREM| LASTIP
| LASTIP| PICS3D
| PICS3D| PROCOM
| PROCOM| CROSSLIGHTVIEW
| CROSSLIGHTVIEW
2. Process simulation
Mesh and doping profile of the device
©©2010
2010Crosslight
CrosslightSoftware,
Software,Inc.,
Inc.,Burnaby,
Burnaby,BC,
BC,Canada
Canada www.crosslight.com
www.crosslight.com
APSYS
APSYS| CSUPREM
| CSUPREM| LASTIP
| LASTIP| PICS3D
| PICS3D| PROCOM
| PROCOM| CROSSLIGHTVIEW
| CROSSLIGHTVIEW
2. Process simulation
2D cut of structure and doping profile at z=40μm.
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
3. Physical models and parameters
Doping-dependent carrier mobilities in simulation are defined by:
electron_mass value=0.76*me
hole_mass value=2.52*me
max_electron_mob(μ2n) value=20.e-4 m2/(V*s)
min_electron_mob (μ1n) value=1.e-4 m2/(V*s)
max_hole_mob (μ2p) value=5.e-4 m2/(V*s)
min_hole_mob (μ1p) value=1.e-4 m2/(V*s)
©©2010
2010Crosslight
CrosslightSoftware,
Software,Inc.,
Inc.,Burnaby,
Burnaby,BC,
BC,Canada
Canada www.crosslight.com
www.crosslight.com
APSYS
APSYS| CSUPREM
| CSUPREM| LASTIP
| LASTIP| PICS3D
| PICS3D| PROCOM
| PROCOM| CROSSLIGHTVIEW
| CROSSLIGHTVIEW
3. Physical models and parameters
Trap settings are essential for modeling of a-Si devices. Four kinds of traps are
used here:
trap_conc_2 value=1.e23 /m3
traplevel_tail_2 value=0.05 eV
trap_ncap_2 value=2.e-21 m2
trap_pcap_2 value=5.e-20 m2
trap_conc_4 value=1.e22 /m3
traplevel_stddev_4 value=0.1 eV
trap_ncap_4 value=2.e-21 m2
trap_pcap_4 value=5.e-20 m2
trap_conc_3 value=1.e23 /m3
traplevel_tail_3 value=0.05 eV
trap_ncap_3 value=5.e-20 m2
trap_pcap_3 value=2.e-21 m2
trap_conc_5 value=1.e22 /m3
traplevel_stddev_5 value=0.1 eV
trap_ncap_5 value=5.e-20 m2
trap_pcap_5 value=2.e-21 m2
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
3. Physical models and parameters
Trap Models
0.7eV
•Traps labeled #2 and #4 are acceptor levels.
•Traps labeled #3 and #5 are donor traps.
Trap_2:
• Due to broadening of the
conduction band.
Conduction
• Energy level has an exponential
tail.
Trap_4 & Trap_5 :
• Due to dangling Si-Si bonds.
• Energy level has a Gaussian
distribution.
1.78eV
0.88eV
Valence
Trap_3:
• Due to broadening of the
valence band.
• Energy level has an exponential
tail.
©©2010
2010Crosslight
CrosslightSoftware,
Software,Inc.,
Inc.,Burnaby,
Burnaby,BC,
BC,Canada
Canada www.crosslight.com
www.crosslight.com
APSYS
APSYS| CSUPREM
| CSUPREM| LASTIP
| LASTIP| PICS3D
| PICS3D| PROCOM
| PROCOM| CROSSLIGHTVIEW
| CROSSLIGHTVIEW
4. Results
Current density distribution
@ gate voltage=15 V
@ drain voltage=25 V
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
4. Results
Potential distribution
@ gate voltage=15V
@ drain voltage=25V
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
4. Results
Threshold voltage
Threshold voltage close to 1V
Drain Current (A)
Drain Current (A)
@ Drain voltage=0.5V
@ Drain voltage=5V
Yellow solid line is
automatically generated by
software to extract
threshold voltage.
Gate Voltage (V)
Gate Voltage (V)
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
4. Results
Id-Vd family of curves
Drain Voltage (V)
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW
© 2010 Crosslight Software, Inc., Burnaby, BC, Canada www.crosslight.com
APSYS | CSUPREM | LASTIP | PICS3D | PROCOM | CROSSLIGHTVIEW